Process of smelting ores in blast-furnaces.



Rm 0 9 1 L 2 nm. E F D E T N E T A P m J N 0 S N H O J H .J

PROCESS OF SMELTING ORE S IN BLAST FURNACES.

APPLIOATION FILED APR.9, 1903.

2 SHEETS-SHEET 1.

No. 783,044. PATENTED FEB. 21, 1905.

J. E. JOHNSON, JR- I PROCESS OF SMELTING ORES IN BLAST FURNACES.

APPLICATION FILED APR. 9, 1903.

2 SEEETSSHEBT 2.

UNITED STATES Patented February 21, 1905.

PATENT OFFICE.

PROCESS OF SMELTING ORES -lN BLAST-FURNACES.

SPECIFICATION forming part of Letters Patent No. 783,044, dated February21, 1905.

Application filed April 9. 1903. Serial No. 151,763.

To 1!, whom, it nutg concern:

Be it known that I, J osnrn E. JOHNSON, Jr. a citizen of the UnitedStates, and a resident of Longdale,in the county of Alleghany and Stateof Virginia, have invented certain new and useful Improvements inProcesses of Smelting Ores in Blast-Furnaces, of which the following isa specification.

My invention relates to a process of treating ore in a blast-furnace;and its novelty consists in the several successive steps of the process.

In a blast-furnace of common form the fuel, ore. and flux are so chargedas to form successive approximately horizontal layers extendingsubstantially across the entire area of the furnace. The stock descendsthrough the furnace in approximately horizontal alternating layersextending from wall to wall of the furnace; but after it has passed intothe zone of fusion the fuel is the only one of the materials chargedwhich remains solid, the others in the form of iron or slag melting andrunning down through the mass of incandescent fuel into the well orcrucible at the bottom of the furnace. The blast enters just above thisand unites with the fuel to form carbon monoxid, which passes up throughthe materials as they descend and is there oxidized to a greater degree,forming mixtures of carbon monoxid and dioxid of proportions difieringwith the circumstances.

It is a fact that a mixture of carbon dioxid and carbon monoxid behavesduring a considerable range of temperatures in a precisely oppositemanner in the presence of free carbon and in the presence ofoxygen-bearing ores and within a certain wide range of temperatures. Inthe first place, in the presence of free carbon-for instance, in theform of fuel-the carbon dioxid absorbs an amount of carbon equal to thatwhich it already contains and becomes carbon monoxid. In the secondplace, in the presence of oxygenbearing ores for instance. hematitea'portion of the carbon monoxid absorbs oxygen therefrom and becomescarbon dioxid. It follows from these reactions that as the gasesresulting from the combustion of the fuel consisting almost wholly as tocombustible elements of carbon monoxid initially pass upward through thefurnace they are subjected to rapidly-alternating conditions havingprecisely opposite tendencies, and any oxidation of the fuel which goesbeyond the monoxid stage is effected under difficulties. The result ofthis condition of things is that in ordinary good practice aboutone-third of the carbon entering the furnace as fuel is oxidized to thedioxid stage. Another result is that the carbon derived from the flux(carbonate of lime) is liberated therefrom in the form of carbon dioxid,and consequently after undergoing the reactions referred to passes outof the furnace as two-thirds monoxid and onethird dioxid. Thesereactions mean a loss of heat and of carbon from the fuel. It is obviousthat if some of these disadvantageous reactions could be prevented agreat economy in 'fuel could be secured, and it is furthermore obviousthat they can be prevented if the gases resulting from the combustion ofthe fuel after the desirable reactions necessitating contact of the fueland ore have taken place are prevented from coming subsequently intocontact with the incoming fuel and confined to contact with the incomingore or ore and flux. The first step of my process therefore consists inmaking the gases resulting from the combustion of the fuel pass throughthe incoming ore and flux alone and out of contact with the incomingfuel immediately before being discharged from the furnace. In ordinaryblast-furnaces also it is evident that it is necessary to secure acertain temperature, which for the sake of convenience I will call thecritical temperature, below which it is impossible to accomplish thedesired reactions between the fuel, the gases'derived therefrom. theore, and the flux. The energy expended in bringing the products ofcombustion up to this critical temperature is therefore unavailable forthese reactions which can only take place at or above that temperature,though it is useful in the preparatory or preliminary reactions of theprocess which occur at lower temperatures. The

efficiency of the furnace depends much upon the amount of heat availableabove this critical temperature. hthout going into any detaileddiscussion of the matter or presenting in detail facts which are wellknown to blastfurnace engineers I may state that it is a fact that muchof the heat which would otherwise be available for use in thisconnection is carried off by the nitrogen derived from the air of theblast and that a smaller though important quantity of the heat is usedin decomposing the moisture accompanying the aircurrent. It is obvious,therefore, that if the amount of nitrogen and moisture commonly presentin the blast could be reduced the amount of heat available for theefficient working of the furnace would be increased. This leads me toanother step of my invention, which consists in supplying the blast witha current of, air rich in oxygen and substantially free from moisture,and thus obtaining the advantages referred to.

I carry out the process referred to in the form of apparatus illustratedin the accompanying drawings; but it will be understood that I do notlimit myself to the mechanical devices here illustrated, because whenthe principles underlying my invention are once understood the skilledblast-furnace engineer can probably devise a number of forms ofapparatus for use in carrying out the process founded thereon.

In the drawings, Figure 1 is a central vertical section of ablast-furnace embodying my improved apparatus; Fig. 2 is a section andpartial perspective of the ore-hopper, and Fig. 8 is a bottom plan viewof the mantle.

In the drawings, 1 is the stack, of usual construction, provided with ahearth 2, crucible 3, twyers 4 4, blast-pipes 5, and boshes 6 6. 7 isthe throat of the stack. All of these parts are constructed in the usualmanner common to the art and need no detailed or other description.

Suitably supported at the mouth of the stack is a platform 20, to. whichthe ore is con veyed and from which it is dumped into a conical hopper200, and from this hopper it is fed into the stack as required. At oneor more points in the stack there are flues 22 for the removal of thegases, which normally occurs through the down-comer 32 of the customarytype; but one of the fines is carried up and ends in a bleeder orexplosion-door 30, 01' both combined, which differ but slightly fromthose of the ordinary type.

At the center of the hopper 200 is a vertically-placed mantle 40,composed in its upper portion41 of a cylindrical body and in its lowerportion 42 of a fluted conical body. It

is preferably made of metal with hollow walls,

having between them an annular space 42, adapted for the circulation ofa cooling medium such as water, air, steam, or the likesupplied from asuitable source and coming in and going out through propervalve-controlled pipes 42".

At the top of the mantle 40 is mounted the conical fuel-hopper 43,secured firmly to a framework 44, supported from the stack.

A pusher 45, of hemispherical form and having its plane surfaceundermost and resting upon the upper surface of the fuel, is 'providedfor charging the fuel. Secured to the pusher 45 by a ball-joint 45, withits center approximately in the plane surface of the pusher, is a rod46, extending vertically upward through a bell 47 and itself terminatingin a piston 48, fitting snugly within the cylinder 49, mounted upon theupper frame of the stack. The pusher 45 has an opening in its top toadmit of a movement relative to the rod, the opening being covered by afixed collar 45", of corresponding shape, fast on the rod 46. Thisconstruction enables the pusher to accommodate itself to the surface ofthe fuel I within the hopper 43 without danger of leaving a gap at theside past which the fuel can be crowded. The pusher 45 is operated bythe piston 48 in the cylinder 49, a pressure being maintained of such anamount upon the upper side of the piston as will cause the quantity offuel to be discharged from the mantle which will be properlyproportioned to the quantity of ore passing the lower end thereof at thesame time. Thecylinder 49 is provided with suitable valve-controlledinletpipes 49, 49 and 49 In order to charge the fuel, it is put into thehopper 43 above the bell 47. The bell 47 is then raised by admittingsteam through the pipe 49 to raise the piston 47 allowing the fuel tocome in on top of the pusher 45, the latter being in the position shownat the bottom of the fuel-hopper. The bell is then closed and the pusher45 raised to its highest position by admitting the steam through thepipe 49, allowing the fuel to enter the mantle 40 below it. It is 'then'sent down until it reaches the fuel and establishes the desired pressureupon it, following it down with the fuel until the bottom of its strokeis reached, when the operation is repeated.- It will of course beunderstood that the pressure in the cylinder 49 is variable at will.

The bell 47 is provided with an annular rod 47, extending upward andsurrounding the rod 46 and terminating in a piston 47", fitting snuglywithin the cylinder 49 and below the piston 48. I have not shown anymeans for operating the bell 47 because this is a common form andinvolves nothing new. It will be observed that this constructionprovides substantially a means for feeding the fuel which constitutes alock or gas seal intermediate between the mantle and the source offuel-supply.

The mantle 40 is fluted at its lower portion, the change being gradualand the outer extremities of the flutes being divergent rather than theinner ones being convergent from the line of the initial cylinder. Thismight be otherwise expressed by saying that the inner lobes of theflutes do not fall much, if any, within the initial cylinder, while theouter lobes are tangent to a divergent cone outside of it. The result ofthis form of mantle is that the fuel is discharged therefrom in a flutedor star-shaped column surrounded on all sides by the descending ore,which comes down between the external surface of the mantle and theinner wall of the stack. An intimate contact between the ore and fuel isthus effected.

The ore-charger consists of the conical hopper 200, secured to thestack, and the bell 21, terminating in the sleeve 51, which fits snuglyaround the cylindrical portion 41 of the mantle 40. Brackets 52 aresecured to the bell at suitable points and in turn are secured to theforks 53 of a lever 54, fulcrumed in suitable bearings at the side ofthe stack and which lever is actuated bya piston-rod 55, terminating ina piston 56, which moves in a cylinder 57 and is controlled by fluids,such as steam, which may be admitted and discharged through thevalve-controlled pipes 57 and 57 The movement of the bell 21 withrelation to the conical hopper 200 provides an opening the control ofwhich by means of the lever 54 is simple and enables the operator togage the amount of ore fed with accuracy. The upper edge of the sleeve51 abuts against an annular shoulder on the mantle and makes a tightfit.

In the improved form of furnace if the mantle and the furnace outside ofit were both kept full to an approximately constant height theproportion between the fuel and the ore charged would be determined bythe areas inside and outside of the mantle at its lower end and theweights of the respective columns of materials above these areas andwould be approximately constant,whether right or wrong, if no provisionwere made to vary this ratio. The ore being heavier than the fuel willtend to cut off the descent of the fuel, and the column of the fuel istherefore made higher to compensate for this. The purpose of the piston48 and pusher 45, which works with a free fit within the cylindricalportion of the mantle 40 and presses upon the fuel, is introduced as anadjustable factor to enable the ratio of. the amount of ore and fuelcharged into the furnace to be controlled.

I have invented a form of apparatus and sundry processes carried outtherein whereby there can be economically and readily extracted from theatmosphere a large proportion of its oxygen. This invention forms nopart of the present invention and forms the subject-matter of anotherapplication for Letters Patent of the United States, Serial No. 154,945,filed April 30, 1903. The supply of oxygen which I thus secure isintroduced into the twyers and blast-pipes of the furnace illustratedand is forced into the bottom of the furnace by means of a blowingengineof any suitable type and which needs no specific description. Thequantity of oxygen giving the most successful results in practice variesgreatly with different conditions even with the same furnace and incomparatively brief intervals and the purity of the oxygen obtainablebeing regulable by the adjustment of my apparatus for producing it suchregulation takes the place of the regulation of the temperature of theblast now commonly practiced. Under all normal conditions, however, theoxygen in the blast will be associated with much less nitrogen thanoccurs with atmospheric air. By using this oxygen-laden gas as thematerial forthe blast I can do away with the heating-stoves now requiredfor the blast and with many of the accessories thereto, with a resultingeconomy.

In the present form of furnace using the existing methods of filling asthe fuel forms continuous layers across the furnace it is necessary thatthe blast be able to traverse these. In fact, the openness of the fuelis the principal factor in case of driving the blast and the gasesresulting therefrom up through the furnace, which is a very importantpoint in the practical operation of furnaces. For this reason coke hascome to be the principal blastfurnace fuel and few kinds of coal can beused. On account of their bituminous nature it is impossible to use mostsoft coals, because when they become hot they stick together andpractically seal the furnace up, making the passage of the gasesimpossible. By my method of filling, however, the fuel is charged in acontinuous column of fiuted cylindrical section through which there isno necessity that the gases should pass, it being, in fact, undesirablethat they should do so to any great extent, and accordingly bituminousfuels are workable and even desirable, the fact that they cohere intoone solid mass when hot protecting them largely from the dissolvingaction of carbon dioxid. The fuel column being in the center of thefurnace is also out of contact with the walls of the same, and thereforeany possibility of hanging by the adherence of the fuel to the wall isthereby prevented. The gaseous products resulting from the distillationof the coal as it is heated, which are very combustible and have apowerful deoxidizing effect, pass up through the column of ore andassist in the mode of deoxidation.

It is to be noted that I do not employ a blast containing an excess ofoxygen to raise the temperature in the furnace, but to increase theamount of heat which is at the critical high temperature requisite forperforming that part of the smelting operation which can only take placeat the highest temperature produced in blast-furnaces employing anairblast. NVhile the necessary temperature can be kept up in theordinary blast-furnace in which the charge contains fuel throughout, thecomplete oxidation of the escaping gases by finally passing them throughan incoming body of ore containing no fuel requires an additional supplyof high-temperature heat to prevent the temperature of the escapinggases from being; reduced to a point where they will no longer react onthe ore. There is thus a true combination between the step of supplyinga blast containing an excess of oxygen and that of passing the escapinggases through a body of ore containing no fuel. The gases escaping frommy furnace are high in carbon dioxid and low in carbon monoxid andnitrogen, the fuel being fully oxidized and the heat evolved by thereaction being utilized for reduction rather than in heating such largeamounts of nitrogen as are present in the ordinary air-blast. The use ofa blast which is substantially free from water also decreases the heatlosses and adds to the effectiveness of the other steps of the process.

The use of a mantle or fuel-chute which is provided with cooling meansmakes it possible to use bituminous coal, which would otherwise adhereto thechute as soon as it began to distil and impede or prevent the fuelfrom being fed into the furnace.

hat 1 claim as new isl. The process of smelting ores in a blastfurnace,which consists in feeding separate bodies of ore and fuel into thefurnace, smelting the charge and increasing the amount of heat availablefor smelting, and especially for these reactions which require a hightemperature, by supplying a blast containing an excess of oxygen, andutilizing the heat in the fuel by passing the gases escaping from thefurnace through the incoming body of ore and maintaining them out ofcontact with the incoming fuel, the waste gases thus being high incarbon dioxid and low in carbon lnonoxid and nitrogen, as set forth.

2. The process of smelting ores in a blastfurnace, which consists infeeding separate bodies of ore and fuel into the furnace, smelting thecharge and increasing the amount of heat available for smelting, andespecially for those reactions which require a high temperature, bysupplying a blast containing an excess of oxygen and substantially freefrom water, and fully utilizing the heat in the fuel by passing thegases escaping from the furnace through the incoming body of ore andmaintaining them out of contact with the incoming fuel, the waste gasesthus being high in carbon dioxid and low in carbon monoxid and nitrogen,as set forth.

3. The process of smelting ores in a blastfurnace, which consists insupplying to the charge a blast containing an excess of oxygen, andvarying the proportion of oxygen in the blast in accordance with thevarying conditions in the furnace, as set forth.

4:. The process of smelting ores in a blastfurnace, which consists insupplying to the charge a blast containing an excess of oxygen andsubstantially free from water, and varying the proportion of oxygen inthe blast in accordance with the varying conditions in the furnace, asset forth.

5. The process of smelting ores in a blastfurnace, which consists inintroducing separate bodies of ore and fuel by gravity into the top ofthe furnace, and controlling the ratio of the amounts of ore and fuelsupplied by increasing the pressure on the body of fuel to compensatefor the difference in the specific gravity of the fuel and ore. as setforth.

6. The process of smelting ores in a blastfurnace, which consists infeeding separate bodies of ore and fuel into the furnace, the fuel beingsupplied in the form of a column having laterally-projecting portionswhich extend into the surrounding body of ore, whereby an intimatecontact between the ore and fuel is effected, as set forth.

7. The process of smelting ores in a blastfurnace, which consists infeeding separate bodies of ore and bituminous or coking fuel into thefurnace, the fuel being supplied in the form of a solid column havingfluted portions which extend into the surrounding body of ore, wherebyan intimate contact between the ore and fuel is effected and the gasesdistilled from the fuel are compelled by the relative imymnetrability ofthe column of fuel to pass through the ore and are thereby effectivelyutilized for reduction, as set forth.

8. The process of smelting ores-in a blastfurnace, which consists infeeding a column of fuel into the furnace through a conduit, feeding theore into the furnace around the column of fuel, and cooling the surfaceof the column of fuel to prevent its adhesion to the walls of saidconduit, as set forth.

\Vitness my hand, this 19th day of March, 1903, at Longdale, in thecounty of Alleghany and State of Virginia.

JOSEPH E. JOHNSON, J11.

\Nitnesses:

S. R. ROBINSON, XV. Al (J. JONES.

